Compression Moulding can only be used with which type of plastics?

Compression moulding is a process typically used with thermosetting plastics, which are a type of polymer that hardens when heated and cannot be remoulded once set. This technique involves placing the pre-measured material into a heated mould, where heat and pressure cause the material to flow and fill the mould before undergoing a chemical change that hardens it into its final form.

Thermosetting plastics are ideal for this process because they require specific conditions of heat and pressure to ensure proper curing and to achieve the desired material properties, such as strength and resistance to heat. Once cured, thermosets are rigid and stable under heat, making them suitable for a wide range of applications, from electrical housings to automotive components.

In contrast, thermoplastics can be re-melted and re-formed when heated, elastomers maintain their rubber-like properties even under stress, and bioplastics can vary widely in their characteristics and processing methods. Therefore, the specific properties and behavior of thermosetting plastics align perfectly with the requirements of the compression moulding process, making it the correct answer.